Bogging, Sputtering, with a hint of Backfiring!

[blackout240]

K so blew my old KA engine and put new one in, wouldnt run for about 2 weeks. After going through every inch of this engine we finally found the problem and it was a bad distributer. So ive been driving it for about a week now and decided to race a civic, won by the way, and since that race it revs up to 5500-6000rpms and sounds like its hitting rev limiter, actually kinda sounds like im boostin. Now at 1500-2500rpm it chuggs and sputters with a hint of backfire. . . . . . . . . . does anyone know what this could be? Checked the MAFS but its fine.
Modified by blackout240 at 7:46 PM 7/7/2008

[qksilver1]

Sounds like the distrb might have moved and threw off your timing.